Comparison of the terpene lactones and flavonols contents in G. Biloba commercial samples and the NIST standard reference materials using LC/UV/MS

Abstract

The leaf extract of Ginkgo biloba has purported value for improving mental capacities in Alzheimer's patients. The flavonols and the terpene lactones are considered to be the two major groups of active components that influence human health. Almost all the clinical studies regarding G. Biloba were using either EGb 761®, a proprietary extract of G. Biloba leaves, or an extract prepared according to the standard set by it. Consequently, most of the commercial G. Biloba products were labeled with their content accordingly. This paper studied the compositions of both flavonols and terpene lactones of seven commercially available G. Biloba products and three standard reference materials (SRM 3246 G. Biloba leaves, SRM 3247 G. Biloba extract, and SRM 3248 G. Biloba tablet) from the National Institute of Standards and Technology (NIST). In this study, a chromatographic method with UV and mass spectroscopic detection was employed for the determination of the compositions of flavonols and the terpene lactones in Ginkgo products using gradient reversed-phase HPLC. Methanol-water (1:1) extracts of terpene lactones and flavonols out of G. Biloba products and NIST SRMs were analyzed qualitatively and quantitatively. While the relative compositions of the flavonol glycosides were similar for the NIST SRMs, those for the commercial G. Biloba products varied significantly. The relative concentrations of terpene lactones were also shown significant differences among products, but not as dramatic as that of flavonols.